Bone rifling system and method of preparing a bone using such system

Abstract

A bone rifling system for use in prosthesis, which allows improved prosthetic bone fixation. The system comprises orthopedic undercut reamer, which can cut controlled internal groove circles or spiral grooves on the internal surface of host bone. The system converts the commonly reamed smooth bone to grooved or rifled bony tube. Used together with bone cements, the bone rifling system ensures prosthetic bone fixation by significantly increasing the pull out strength, and decreasing the rate of clinical loosening and failure of replacement joints. Also disclosed is a method for preparing a bone for a prosthesis using such a bone rifling system to cut grooves in a host bone for increased prosthetic bone fixation.

I claim: 
     
       1. A bone rifling system (BRS) for use in placing an endoprosthesis, including an orthopedic undercut reamer comprising;
 a guide tube having a proximal and distal end, 
 a cutter bar having at least one cutter extending from a portion of said cutter bar, said cutter bar positioned within said guide tube between the proximal and distal ends of said guide tube and displaceable to extend said at least one cutter from an outer surface of said guide tube; 
 an engager adapted to control the displacement of said cutter bar and engage the cutter with an internal surface of a bone; 
 a cap adapted to close the proximal end of the guide tube; and 
 at least one semi-cylinder positioned within said guide tube and adapted to displace said cutter bar, 
 wherein said engager further includes at least one engagement rod extending from said engager through said cap; and 
 the at least one semi-cylinder displaces the cutter bar in response to movement of said engagement rods. 
 
     
     
       2. The bone rifling system of  claim 1 , wherein said guide tube includes at least one opening in a side wall thereof adapted to receive said at least one cutter of said cutter bar. 
     
     
       3. The bone rifling system of  claim 2 , wherein said at least one cutter extends out through said at least one opening in the guide tube exposing said at least one cutter to cut at least one groove on the internal surface of a bone. 
     
     
       4. The bone rifling system of  claim 3 , wherein said at least one cutter is retractable through said at least one opening in said guide tube to disengage said cutter from the bone after cutting, allowing the reamer to be removed from the bone before placement of the endoprothesis. 
     
     
       5. The bone rifling system of  claim 1 , wherein the at least one engagement rod is in contact with said at least one semi-cylinder. 
     
     
       6. The bone rifling system of  claim 1 , wherein the at least one semi-cylinder includes a pair of semi-cylinders having said cutter bar positioned between said semi-cylinders, wherein said engager includes at least two engagement rods. 
     
     
       7. The bone rifling system of  claim 6 , wherein said cutter bar includes at least one guide pin and at least one of said semi-cylinders includes at least one guide slot such that said at least one guide slot receives said at least one guide pin adapted to control the displacement of said cutter bar. 
     
     
       8. The bone rifling system of  claim 7 , wherein said cutter bar includes a plurality of guide pins and said semi-cylinders include a corresponding number of guide slots adapted to receive a respective one of said guide pins for controlling the displacement of said cutter bar. 
     
     
       9. The bone rifling system of  claim 6 , wherein said guide tube includes two or more openings in a side wall thereof adapted to receive said two or more cutters of said cutter bar, respectively,
 wherein said two or more cutters extend out through said two or more openings in the guide tube exposing said two or more cutters to cut two or more grooves on the internal surface of a bone. 
 
     
     
       10. The bone rifling system of  claim 1  wherein said cap includes a shank extending therefrom away from said guide tube and a power source can be connected to said shank to rotate said guide tube and cutter bar for cutting the bone. 
     
     
       11. The bone rifling system of  claim 10  wherein said engager is positioned on said shank and said engagement rods extend substantially parallel to said shank. 
     
     
       12. The bone rifling system of  claim 10 , wherein the undercut reamer can cut circular grooves or spiral grooves in the internal surface of the bone to a increase fixation strength between the bone and the endoprothesis. 
     
     
       13. The bone rifling system of  claim 1 , wherein the cap is mechanically fastened to the guide tube when the at least one cutter is extended from the outer surface of the guide tube. 
     
     
       14. The bone rifling system of  claim 1 , wherein the cutter bar has two or more cutters each extending from a portion of said cutter bar. 
     
     
       15. The bone rifling system of  claim 14 , wherein said guide tube includes two or more openings in a side wall thereof adapted to receive said two or more cutters of said cutter bar, respectively,
 wherein said two or more cutters extend out through said two or more openings in the guide tube exposing said two or more cutters to cut two or more grooves on the internal surface of a bone. 
 
     
     
       16. A bone rifling system (BRS) for use in placing an endoprosthesis, including an orthopedic undercut reamer comprising;
 a guide tube having a proximal and distal end, 
 a cutter bar having at least one cutter extending from a portion of said cutter bar, said cutter bar positioned within said guide tube between the proximal and distal ends of said guide tube and displaceable to extend said at least one cutter from an outer surface of said guide tube; 
 an engager adapted to control the displacement of said cutter bar and engage the cutter with an internal surface of a bone; 
 a cap adapted to close the proximal end of the guide tube; and 
 at least one semi-cylinder positioned within said guide tube and adapted to displace said cutter bar, 
 wherein said engager further includes at least one engagement rod extending from said engager through said cap; 
 wherein said at least one engagement rod engages said at least one semi-cylinder through said cap to provide a pushing force, to displace the semi-cylinder in relation to the guide tube in a substantially axial direction of the guide tube and the cutter bar in a substantially radial direction of the guide tube. 
 
     
     
       17. The bone rifling system of  claim 16 , wherein the at least one semi-cylinder includes a pair of semi-cylinders having said cutter bar positioned between said semi-cylinders, wherein said engager includes at least two engagement rods. 
     
     
       18. The bone rifling system of  claim 17 , wherein said cutter bar includes at least one guide pin and at least one of said semi-cylinders includes at least one guide slot such that said at least one guide slot receives said at least one guide pin adapted to control the displacement of said cutter bar. 
     
     
       19. The bone rifling system of  claim 18 , wherein said cutter bar includes a plurality of guide pins and said semi-cylinders include a corresponding number of guide slots adapted to receive a respective one of said guide pins for controlling the displacement of said cutter bar. 
     
     
       20. The bone rifling system of  claim 16 , wherein the cutter bar has two or more cutters each extending from a portion of said cutter bar. 
     
     
       21. The bone rifling system of  claim 20 , wherein said guide tube includes two or more openings in a side wall thereof adapted to receive said two or more cutters of said cutter bar, respectively,
 wherein said two or more cutters extend out through said two or more openings in the guide tube exposing said two or more cutters to cut two or more grooves on the internal surface of a bone. 
 
     
     
       22. A bone rifling system (BRS) for use in placing an endoprosthesis, including an orthopedic undercut reamer comprising:
 a guide tube having a proximal and distal end, 
 a cutter bar having at least one cutter extending from a portion of said cutter bar, said cutter bar positioned within said guide tube between the proximal and distal ends of said guide tube and displaceable to extend said at least one cutter from an outer surface of said guide tube; 
 a cutter extension mechanism adapted to displace the cutter bar and extend the at least one cutter into an internal surface of a bone; 
 a cap adapted to close the proximal end of the guide tube; and 
 at least one semi-cylinder positioned within said guide tube and adapted to displace said cutter bar, 
 wherein the at least one semi-cylinder is displaced in relation to the guide tube in a substantially axial direction of the guide tube to displace the cutter bar in a substantially radial direction of the guide tube. 
 
     
     
       23. The bone rifling system of  claim 22 , wherein the cutter bar has two or more cutters each extending from a portion of said cutter bar.